The present invention relates to a disk drive for reducing the flutter generated by an airflow as the disk rotates.
An information storing and reproducing device using various types of media such as optical disks and magnetic tapes are known in the art. Among them, hard disk drives (HDDs) have become popular as storage devices for computers to such an extent that they are one type of the storage device indispensable for today's computers. Further, not limited to computers, HDDs are expanding more and more in application because of its excellent characteristics. For example, HDDs are used for moving picture recording/reproducing devices, car navigation systems, cellular phones, removable memories used in digital cameras and so on.
The hard disk drive comprises a magnetic disk for storing data, a head for performing data read and/or write between it and the magnetic disk, and an actuator for moving the head to a desired position on the magnetic disk. The actuator is driven by a voice coil motor and pivotally moved about a pivot shaft to thereby move in the radial direction on the rotary magnetic disk. Thus, the head can get access to a desired track formed on the magnetic disk to perform read/write data.
Incidentally, the interface of the head and disk within a mechanism portion (HDA: Hard Disk Assembly) is closed by the base and top cover of HDD. Therefore, it is necessary to remove lubrication oil leaked out of the actuator for driving the magnetic head, or dust possibly generated due to the wear of the drive mechanism. Accordingly, a circulating filter for collecting the dust is arranged where a pressure difference within the HDA is generated. When the magnetic disk rotates, an airflow is generated at the outer edge portion of the disk in the rotating direction of the disk, and the airflow passes through the circulating filter, thereby removing dust contained in the airflow.
A higher degree of tracking accuracy is desired as the shorter pitch of the recording track of HDD's progresses, but the vibration of the magnetic disk at the time of rotation greatly affects the accuracy of the tracking operation. In the HDA, an airflow smoothly flows as the disk rotates by a flow straightening wall provided along the outer edge portion of the disk. This flow straightening wall is preferably as continuous as possible, whereby the vibration of the disk generated by the airflow can be suppressed. However, when the above-described circulating filter is arranged, for example, at a corner of the HDA or the like, the flow straightening wall is normally discontinuous at the corner. This is because there is needed an inlet for causing an airflow to flow into the circulating filter, and an outlet for causing an airflow to flow out from the circulating filter.
In the hard disk drive described in Patent Document 1 (Japanese Patent Laid-Open No. Hei 5-347089), there is provided a guide portion for guiding an inflow airflow so as to produce a height between the disks. The hard disk drive according to the technology described in Patent Document 1 is shown in FIGS. 12(a) and 12(b). As shown in FIGS. 12(a) and 12(b), in the hard disk drive, a gap 903 is provided between an outer edge portion 901a and a flow straightening wall 902 of a hard disk 901. An airflow which flows through a dust collecting filter 904 flows out along the lower surface of the hard disk 901, and flows out to the upper surface of the hard disk 901 passing between the edge surface of the outer edge portion 901a of the hard disk 901 and the gap 903. Therefore, the hard disk 901 vibrates when the airflow moves toward the upper surface of the hard disk 901, and hits the edge surface of the outer edge portion 901a of the hard disk 901. According to the technology of Patent Document 1, because the rising airflow cannot be controlled positively, it is not possible to positively suppress the vibration, with respect to the hard disk, generated by the rising airflow.